There are many beneficial drugs known to medicine, veterinary and pharmacy that are administered for producing a beneficial effect that often have a serious shortcoming associated with their use. For example, the electrolyte drug potassium chloride is the pharmaceutically acceptable salt most frequently used when the benefit of the potassium cation is desired for its indicated therapeutic effect. Potassium chloride is used when hypokalemia exists, as a treatment with certain diuretics, in steroid therapy, and for relieving the symptoms associated with Menier's disease. However, serious shortcomings are associated with its use, mainly potassium chloride is an irritant of gastrointestinal mucosa, and its use often leads to bowel lesions. Another important drug that possesses similar shortcomings is aspirin. Aspirin, or acetylsalicylic acid, is used widely as an antipyretic and as an analgesic in a variety of medical conditions. Aspirin is a very valuable drug; however, the use of this drug in conventional dosage forms often is accompanied by gastrointestinal irritation. Another drug whose usefulness is compromised by unwanted effects is indomethacin. Indomethacin exhibits both analgesic and anti-inflammatory properties and it is used mostly for the treatment of rheumatoid arthritis. The most frequent unwanted actions associated with dosage forms containing this drug are gastrointestinal mucosal disturbances similar to those mentioned immediately above.
Other drugs, such as the nonsteroidal, anti-inflammatory, pharmaceutically acceptable salts of ibuprofen, diclofenac, naproxen, fenoprofen, and the like are widely used for the treatment of inflammatory conditions, but they also suffer from the disadvantage that they can cause irritation of the mucosal lining of the digestive tract. Then, too, the widely used antiscurvy vitamin, ascorbic acid, is known to elicit a similar irritation in warm-blooded animals, including humans. In many instances the irritation occurs as a result of an irritant producing drug being presented in a concentrated dosage form directly to the lining of the digestive tract, prior to diluting the drug with digestive fluids.
The prior art has provided novel therapeutic systems manufactured in the form of osmotic devices for the precision administration of drugs at controlled delivery patterns over extended operational delivery times. These unique systems are disclosed in U.S. Pat. Nos. 3,845,770 and 3,916,899, both issued to patentees Theeuwes and Higuchi. The systems disclosed in these patents comprise a semipermeable wall that surrounds a compartment containing a drug that is dispensed through at least one exit passageway in the wall. The dispensing system disclosed by Theeuwes and Highuchi represent an outstanding and pioneering advancement in the delivery art, and they are extraordinarily effective for delivering all kinds of drugs in the form of saturated solutions. While these systems are useful for dispensing innumerable drugs to a biological environment of use, there is an occasional instance where an unexpected advancement is needed in these systems for dispensing potentially irritating drugs of the type mentioned above. Thus, in light of this presentation, it will be appreciated by those versed in the dispensing art that if a practical system is made available for dispensing such beneficial drugs, with a lessening of unwanted effects, such a dispensing system would have a definite use and represent a valuable contribution to medicine, veterinary and the pharmaceutical arts.